Bring anywhere from 10 to 25 people to your raid and the difficulty will automatically scale.

Works with battletags, so you can bring friends from other realms.

Item level of loot is between Raid Finder and Normal and loot is awarded with the Raid Finder style loot system.

Separate lockout from Raid Finder and Normal, allowing you to do all three difficulties.

Originally Posted by Blizzard Entertainment

Raids in World of Warcraft have a long history of not just challenging players, but changing and evolving as the years and expansions go by. As with everything in the game, we’re always thinking about what more we can bring to raiding to improve the experience for an even wider range of players. While Normal and Heroic Raids are a great fit for many, we feel there’s another gap worth filling—and to that end, we’re currently working on the development of a new type of Raid for the next major content update: Flexible Raiding.

One Size Does Not Fit All
While it’s impossible to fit every player into a neat, tidy archetype, we recognize that we could be providing a better experience to one broad category of raider: social groups comprised predominantly of friends and family, and smaller guilds that do their best to include as many members in their Raid outings possible.

During the Wrath of the Lich King expansion, the 10-player Normal difficulty served these groups of players pretty well, but the unification of 10-player and 25-player into a single difficulty effectively eliminated that niche. While Raid Finder mode is extremely accessible, it doesn’t provide smaller groups with a tight-knit social experience while progressing through the content. In Patch 5.4, we’re planning to introduce a new mode of raiding that allows us to deliver the sort of experience that we think these players are looking for.

/Flex
To fill this void, we’re in the process of developing a new Flexible Raid system, which includes a new difficulty that sits between Raid Finder and Normal difficulty, while still allowing friends, family, or pick-up groups to play together. This difficulty will be available for premade groups of 10–25 players, including any number in between. That means whether you have 11, 14, or 23 friends available for a Raid, they’ll all be able to participate.

The Flexible Raid system is designed so that the challenge level will scale depending on how many players you have in the Raid. So if you switch between 14 players one week and 22 the next, the difficulty will adjust automatically. Keep in mind that unlike Raid Finder, no matchmaking is available, so you’ll need to make sure you invite people to attend—but if some can’t make it, it’s not the end of the world (or the Raid). You’ll also still be able to invite Real ID or Battle.net friends cross-realm. Who you choose to bring and what Item Level gear they’ll need to join your merry band is up to you, too—there’s no Item Level requirement for this Raid difficulty.

Dressed to Kill
A new Raid difficulty also means a new Item Level. Flexible mode will award loot with an Item Level that falls between Raid Finder and Normal quality, and will use the Raid Finder’s “per person” loot system, specialization choices, and bonus rolls, so you won’t need to worry about bringing the “wrong” person and having them win that piece of gear you’ve long been waiting for.

You Have the Keys
We plan to unlock the Flexible Raid difficulty in wings, similar to Raid Finder, but on an accelerated timetable. This new difficulty also has a separate Raid lockout from Raid Finder and Normal difficulty, allowing you to take part in all three if you so desire. You’ll also be able to complete portions of your “Glory of the Orgrimmar Raider” raid meta- achievement in Flexible mode as well as in Normal or Heroic to earn cosmetic rewards such as an epic mount. This will allow Raid groups the opportunity to switch off nights between raids to complete achievements. Finally, taking part in Flexible, Normal, or Heroic difficulty will provide access to additional rewards that won’t be available in Raid Finder.

Getting Down to Brass Tacks
As with any in-development feature, we’re continuing to refine how the Flexible Raid system will work, and we look forward to hearing your constructive feedback from your experiences on the Public Test Realm when the new system goes live.

i don't understand this at all. Yeah guys lets take away wotlk style raiding where 10 man was rewarding lower ilvl loot by a fraction and was a little easier for people to play with their friends in in favour of sharing lockouts for 10 and 25. Then lets chuck in raid finder and make it compulsory to gear so that anyone who wants to raid has to do it to get anywhere in the first place. And now lets make ANOTHER mode of the same encounter when all we have done is whinge about how we can't balance 10 and 25 man to be equal in difficulty yet we now can miraculously with any number between 10 and 25...

People complaining about this feature because it doesn't impact them. Worthless people.

This is actually pretty huge. People can bring 15 people to a raid instead of 25 and instead of 10. Imagine if they later add this mode to normal and heroic. No more benching of players. This can be game changing.

Instead of the per person loot it really should be that the bosses will only drop gear that people in the raid can use and don't already have, but the bosses could drop int plate with no hpal in the group but a plate wearer class. And just get rid of LFR and put this in, so much better..

Yeah, this sounds really cool, but I think having fewer than 10 (say, a minimum of 6 or 7?) would be a good addition to this.

Sometimes having only 8 or 9 people to raid is the reason some raid groups fall apart.

Agree, seems kinda pointless to me as a 10-man guild as it won't be something we can do when raids are cancelled/finish early because we ended up a few players short.

Seems kinda good for cheesing glory achvs and not a lot else - kinda not happy with the idea of needing to do LFR, LFR+ and normal raids every week if we're after trinkets/tier bonuses. Having normal modes scale would have been far more appealing so you could run 12 players for 10-man without the need to sit guys each week.

So this was one of their unannounced features? i must say Lore kept saying that would be a great idea and look they are doing it . This feature won't affect much as im progressing through heroics but its a very welcome addition . thnx blizz !

Interesting implementation. It's only too bad that I can't normally round up more than 8 friends/family to a raid.

There are some things to think about: Raids usually need 2 tanks, at least 2 healers, etc. Wonder if you can still run it with 8 (even though it would scale down to 10), seeing as it's a different difficulty level. Essentially 8-man it.

I would be more interested in this if it weren't limited to just this new difficulty level. My guild is a 10 man guild with 2x 10 man raid teams. We often have one missing from each time on any given night, so we are unable to field a full 25man raid. If this system were available in normal mode, we could merge our two ten man groups into a anywhere between 18-22 man raid each week.